Nova Ori 2019 & Nova Cyg 2019

Alerts and Monitoring of Novae

Nova Ori 2019 & Nova Cyg 2019

Postby Francois Teyssier » Sun Oct 13, 2019 9:08 am

Pages opened in the database:

Nova Ori 2019 = PNV J06095740+1212255
Spectra (visible and near IR) obtained by James Foster

asdb_v5668sgr_20190703_381.png (16.07 KiB) Viewed 556 times

Nova Cyg 2019 = PGIR 19brv = AT2019qwf
Spectrum obtained by Paolo Berardi
at mag V ~ 16.7 !
(following an error: I took the I mag as V mag in AAVSO discussion - Sorry!)

asdb_pgir19brv_20191012_771.png (20.71 KiB) Viewed 556 times

The spectrum is pretty good for such a faint target. Congratulations, Paolo!

François Teyssier
Francois Teyssier
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Re: Nova Ori 2019 & Nova Cyg 2019

Postby Paolo Berardi » Fri Oct 18, 2019 3:57 pm

Thank you François, yesterday I observed again the nova under better weather conditions and a slight more brightness (nova at V 15.98 from concurrent photometry) compared to october 12.


Paolo Berardi
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Re: Nova Ori 2019 & Nova Cyg 2019

Postby Joan Guarro Flo » Sat Oct 19, 2019 9:44 am

Very nice work, Paolo !
Congratulations, Joan.
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Re: Nova Ori 2019 & Nova Cyg 2019

Postby Francois Teyssier » Mon Nov 04, 2019 7:49 am

We report on optical spectroscopy of AT2019qwf (also known as PGIR19brv and ZTF 19abyukuy) discovered and reported by De et al. (ATEL #13130) in regular survey operation of Palomar Gattini-IR (Moore & Kasliwal 2019) on UT 2019-09-17.25 (but also see ATel #13149). The object was found to be highly reddened with broad emission lines of H alpha, H beta and O I (though numerical values for the line FWHMs were not specified) and hence suggested to be a nova. Further spectroscopy on 2019-09-21 by Lee et al.
(ATel #13149 ) supported the nova classification and determined the FWHM of the H-alpha line to be 840 km/s. This spectrum is reported to be at high resolution so the cited FWHM of 840 km/s should not change much even if it is the observed value and not deconvolved for instrumental broadening (it is not clear whether instrumental broadening has been accounted for).

We recorded optical spectra of AT2019qwf on 2019-11-01.71 using the Mt.
Abu Faint Object Spectrograph and Camera - Pathfinder (MFOSC-P) instrument on PRL 1.2m Telescope at Mt. Abu, India indigenously developed by Srivastava at al. (2018, Proc. SPIE, 10702-163). The spectra were recorded in two modes (1.) Low resolution mode with R ~ 500- 600 covering the 4500-8500A region and (2.) a R = 2000 mode covering 6000-7000A centred around H-alpha.
The low-resolution spectra shows a highly reddened continuum on which we prominently detect H-alpha and the OI lines at 7773A and 8446A. The OI 7773A line shows a P-Cygni profile with ~14 angstroms separation between emission maximum and absorption minimum. Based on the high-resolution spectra, the FWHM of the H-alpha line is measured to be ~ 340 km/s which after deconvolving for the instrument FWHM of 150 km/s gives an intrinsic line width of ~ 300 km/s. The FWZI of the line is ~ 2000 +/- 100 km/s.
The error on the FWHM measurements is +/- 20 km/s.

Thus a considerable narrowing of the line has occurred from the FWHM value of 840 km/s reported in ATel # 13149 making us cautiously speculate whether the ejecta is being decelerated by a surrounding medium. Narrowing of line emission has been seen in other novae as well e.g. Nova Sco 2015 (Srivastava, Banerjee et al. 2015, MNRAS, 454, 1297), and in several recurrent novae with giant secondaries, and such line narrowing has been one of the tracers of the rare class of symbiotic novae. Further observations, especially at high resolution, are thus strongly encouraged to see whether further line narrowing continues. Alternatively this may be a very slow nova in which mass loss continues for a long time (as evidenced by the P-Cyg feature on OI 7773 being present even 45 days after outburst) but at a slower velocity.

The light curve (LC) of the object has been rather peculiar too. After the initial climb to maximum, it has displayed a fairly flat light curve for ~ 25 days followed by a slow but steady brightening of about 1 magnitude over the next 20-25 days as seen from the V and I bands in AAVSO data and in R and g filters as given in a link in ATel # 13149. The LC is reminiscent of the F type light curves of novae (Strope, Schaefer and Henden, 2010) which have an extended interval of nearly constant magnitude at the peak (e.g BT Mon, V849 Oph, DO Aql, HR Del have a flat peak for several months).

The line velocities reported here and in the earlier ATel’s certainly support a nova classification but they are rather low and do not support a He/N class. On the other hand the large reddening makes the detection of Fe II multiplets in the blue part of the spectrum difficult for assigning it as a Fe II class nova. A near-infrared spectrum would be invaluable in this respect as the presence of CI lines in this regime would clearly discriminate between a Fe II or He/N class (Banerjee and Ashok, BASI, 2012).
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